The present invention relates to alkyl esters of 2-fluoro-1-methoxyethylcarbamic acid, which are useful as chemical intermediates, and to a method of preparation of the esters.
The preparation of many biologically active compounds, including pharmaceutical, herbicidal and fungicidal compounds, is greatly complicated by the absence of appropriate chemical intermediates. As a result, the commercial development of these compounds is often delayed or made impractical. Amino acid derivatives containing beta-fluoroethylamine moieties, such as those described in U.S. Pat. Nos. 4,326,071 and 4,528,028, are one such type of compound. The known methods of preparation of these compounds utilize expensive raw materials, generate copious amounts of waste, and are generally unsuited to large scale manufacturing operations. For example, 4-amino-5-fluoropentanoic acid is reported in the Journal of Organic Chemistry, 45, 815 (1980), to be prepared from glutamic acid in a multistep process involving cyclization to a pyrrolidone and subsequent reopening of the ring and concluding with a fluoride exchange using silver fluoride. Better methods of preparation of amino acid derivatives containing beta-fluoroethylamine moieties which avoid these problems would greatly advance the art.